In general, when a vehicle runs on a road at a high speed, drag that is resistant force proportional to the speed, and the area of the vehicle is generated and lift is generated on the vehicle by the air flowing on the car body, so the vehicle is lifted.
The top of a vehicle is curved and the bottom is flat. Accordingly, the speed of the air flowing over the top of the vehicle is greater than the speed of the air flowing under the bottom, so a pressure difference is generated between the top and the bottom of the vehicle, so lift is applied to the vehicle.
In order to solve this problem, in the related art, a rear spoiler is installed on a roof panel or a tailgate of a van or a sports utility vehicle (SUV), or a fixed-type spoiler is mounted on a trunk lid of a general vehicle, thereby preventing the rear portion of the vehicle from being lifted by lift when the vehicle runs at high speed. The fixed-type spoiler increases stability and braking ability when a vehicle runs by offsetting lift, but it increases the resistance of air flowing around the vehicle when the vehicle runs at a low speed, so drivability is deteriorated.
Accordingly, active aerodynamic systems that overcome package limits and are stowed and deployed, depending on the vehicle speed, have been developed. Representatively, there are an active air skirt (AAA) that is disposed behind the front bumper of a vehicle, an active rear spoiler (ARS) that is disposed on the trunk lid, the roof panel, or the tailgate of a vehicle, and an active rear bumper spoiler that is disposed under the rear bumper of a vehicle. However, these devices are being developed and applied as separate (independent) systems, but the relationships between the systems, the optimum shapes of the three combinations, and the optimum logics have not been sufficiently studied.
The description provided above as a related art of the present invention is just for helping understanding the background of the present invention and should not be construed as being included in the related art known by those skilled in the art.